Data transfer is becoming increasingly important, especially between a source and a destination located on a network, such as a wide area network or the internet. Typically, a network comprises a plurality of locations (which intermittently act as sources or destinations) coupled together by a plurality of switching nodes. Switching nodes are used since it is impossible or impractical to connect all locations together directly. The switching nodes are situated between all of the locations for forming communication paths between locations. As such, all of the locations are connected to each other via the switching nodes to provide at least one, and often several communication paths between given locations.
A data packet, which usually comprises a header and a data payload can then be sent between locations via the switching nodes. The header typically contains, among other things, address information which is used to route the data packet through the switching nodes. The data payload contains the actual data that is to be sent between locations. In typical systems, each switching node decodes the header and then switches the data packet onto a proper communication data path so that the data packet can proceed through the switching nodes within the network to the desired destination location.
Several protocol schemes exist for data transfer over networks. The first protocol is referred to as a "store-and-forward" protocol. In this scheme, the data portion of the packet typically follows the end of the header immediately. Since the packet is in electronic form, the packet can be conveniently stored for an arbitrary period of time in electronic memory without signal degradation. The second protocol involves sending out a header to establish a data path before any data is sent. The data portion of the packet is sent only after an acknowledge signal is received from the destination location.
However, these protocols have several disadvantages. First, the "store-and-forward" protocol requires expensive electronic data paths within switching nodes. For example, expensive storage devices are required at each switching node for storage of the header. This is because only one header is used to setup the input/output (I/O) connections in all intermediate switching nodes. In addition, since this protocol routes data electronically, the transmission of the data through the switching nodes is slower as compared with the high link bandwidths achievable with all optical networks.
Next, for the second protocol, not only must the original header be stored at each switching node in electronic memory until the path is setup (similar to the first protocol), but an acknowledge "packet" must also route back to the original source to signal that the path is set up. Also, to add to the complexity, the acknowledge "packet" must be stored at intermediate nodes. Further, similar to the first protocol, transmission of data in a network with electronic routing within switching nodes is slower compared with high link bandwidths of all optical communication. Therefore, these schemes are not well suited for routing optical packets without the use of expensive electronic data paths within the switching nodes and do not have the high link bandwidths of networks with all optical communication paths.
Although some networks attempt to use a combination of optical transmission with optical storage devices, these schemes are impractical because existing optical switches have very slow switching times (typically tens of milliseconds). Consequently, these schemes require transmission storage or delay of the packet for a period of time (the switching time of the slow switch) until the data path is set up. This requires the use of expensive and complex variable optical delay lines. For example, storage/delay of the packet in optical form would require thousands of kilometers of fiber to realize tens of milliseconds of delay. This approach is not only cumbersome to implement but results in signal loss and degradation due to the large amount of fiber traversed.
Therefore, what is needed is a communication protocol that allows the transmission of information between switching nodes in as much optical form as possible without any electronic connections in the data paths of the switching nodes and without expensive optical delay lines. What is further needed is a communication protocol that allows all information transmitted between switching nodes (both control headers and data) to be transmitted optically. What is further needed is a protocol that has high link bandwidths utilizing all optical data packet transmission with the ability to use a variety of data formats without modifications to the hardware in the data path.
Whatever the merits of the above mentioned systems and methods, they do not achieve the benefits of the present invention.